Department of Chemistry and Biochemistry and California NanoSystem Institute (CNSI), University of California, Los Angeles, California 90095, United States.
Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
Inorg Chem. 2022 Sep 26;61(38):15051-15057. doi: 10.1021/acs.inorgchem.2c02116. Epub 2022 Sep 13.
In this work, two pathways of reactivity are investigated to generate site-specific substitutions at the B7 vertex of the luminescent boron cluster, -BH. First, a palladium-catalyzed cross-coupling reaction utilizing the precursor 7-I-BH and a series of model nucleophiles was developed, ultimately producing several B-N- and B-O-substituted species. Interestingly, the B-I bond in this cluster can also be substituted in an uncatalyzed fashion, leading to the formation of various B-N, B-O, and B-S products. This work highlights intricate differences corresponding to these two reaction pathways and analyzes the role of solvents and additives on product distributions. As a result of our synthetic studies, seven new B-based clusters were synthesized, isolated, and characterized by mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. The photoluminescence properties of two structurally similar ether and thioether products were further investigated, with both exhibiting blue fluorescence in solution at 298 K and long-lived green or yellow phosphorescence at 77 K. Overall, this work shows, for the first time, the ability to perform substitution of a boron-halogen bond with nucleophiles in a B-based cluster, resulting in the formation of photoluminescent molecules.
在这项工作中，研究了两条反应途径，以在发光硼簇-BH 的 B7 顶点处生成特异性取代。首先，开发了一种钯催化的交叉偶联反应，利用前体 7-I-BH 和一系列模型亲核试剂，最终生成了几种 B-N-和 B-O-取代物种。有趣的是，该簇中的 B-I 键也可以在无催化剂的条件下取代，导致形成各种 B-N、B-O 和 B-S 产物。这项工作突出了这两种反应途径的复杂差异，并分析了溶剂和添加剂对产物分布的影响。作为我们合成研究的结果，合成、分离并通过质谱和核磁共振（NMR）光谱对七个新的基于 B 的簇进行了表征。进一步研究了两种结构相似的醚和硫醚产物的光致发光性质，它们在 298 K 下的溶液中均表现出蓝色荧光，在 77 K 下具有长寿命的绿色或黄色磷光。总体而言，这项工作首次展示了在基于 B 的簇中用亲核试剂进行硼-卤键取代的能力，从而形成了发荧光的分子。
